1. Field of the Invention
The present invention relates to a resist pattern thickening material which is applied onto a resist pattern and thickens the resist pattern, and which can form a fine space pattern exceeding exposure limits of light sources of existing exposure devices (“space pattern” is hereby defined as a hole, trench, recess, or any other empty space that is formed by a developed (removed) resist). The present invention also relates to a resist pattern, a process for forming the resist pattern, a semiconductor device, and a process for manufacturing the semiconductor device, all of which use the resist pattern thickening material.
2. Description of the Related Art
Conventionally, in manufacturing a semiconductor device, a hole pattern or a line-and-space pattern is formed by using a resist material. In recent years, there has been much research and development of techniques for thickening the resist pattern forming the portions other than the holes in the hole pattern or the line portions in the line-and-space pattern, so as to make the space pattern corresponding to the hole portions in the hole pattern or to the space portions in the line-and-space pattern (i.e., the space pattern formed by the resist pattern) extremely fine. As space patterns have become increasingly fine, the exposure light needed at the time of forming the pattern has changed from lights such as visible light, laser light and the like, to X-rays and electron beams. However, from the standpoint of maintaining good mass produceability, there is a strong demand in continuing to use light (e.g., visible light, laser light and the like) as the exposure light when forming fine patterns. Thus, the development of a method which can efficiently form fine patterns by using deep ultraviolet light, which is light of a short wavelength, as the exposure light has been desired.
Japanese Patent Application Laid-Open (JP-A) No. 10-73927 discloses a technique called RELACS for making a space pattern finer. This technique can form a fine space pattern by using KrF (krypton fluoride) excimer laser (wavelength: 248 nm) which is deep ultraviolet light, as the exposure light of a photoresist (which will hereinafter simply be called “resist”). In this technique, a resist pattern is formed by exposing a resist (a positive resist or a negative resist) to light by using a KrF (krypton fluoride) excimer laser (wavelength: 248 nm) as the exposure light. Thereafter, by using a water-soluble resin composition, an applied film is provided so as to cover the resist pattern. The applied film and the resist pattern are made to interact at the interface thereof by using the residual acid within the material of the resist pattern, and the resist pattern is thickened. (Hereinafter, this thickening of the resist pattern will be referred to upon occasion as “swelling”.) In this way, the distance between the resist patterns is shortened, and a fine space pattern is formed. In accordance with this technique, if a hole pattern is used for example, it is possible to form a fine hole pattern exceeding the exposure limit.
In recent years, the practical application of ArF (argon fluoride) excimer laser (wavelength: 193 nm) as the next-generation exposure light in place of KrF (krypton fluoride) excimer laser (wavelength: 248 nm) has advanced. However, in the above-described technique, it is not possible to use ArF excimer laser as the exposure light, instead of KrF excimer laser. The reason for this is as follows. A resist which is used for KrF excimer laser (hereinafter called a “KrF resist”), which is used as the resist in the above-described technique, is an aromatic resin compound such as a novolak resin, naphthoquinone diazide, or the like. The aromatic rings contained in the aromatic resin compound strongly absorb ArF excimer laser. Thus, even if KrF excimer laser is merely replaced with ArF excimer laser as the exposure light in the above-described technique, the ArF excimer laser cannot pass through the film of the KrF resist. Thus, in the above-described technique, when ArF excimer laser or light of an even shorter wavelength is used as the exposure light, a KrF resist cannot be used, and a resist which is used for an ArF excimer laser (hereinafter called an “ArF resist”) which does not contain aromatic rings must be used.
However, using an ArF resist as the resist in the above-described technique, a problem arises in that the resist pattern cannot be thickened efficiently.
Therefore, the current situation is that there has not yet been developed techniques such as materials, methods and the like which, after forming a resist pattern by using ArF excimer laser as well as KrF excimer laser as the exposure light, can form an applied film on the resist pattern and thicken the resist pattern. The development of such techniques has been desired.